I’m just taking a stab at this since I myself haven’t gotten a hunter past level 19. Good resource database is wow-petopia.com

Ask yourself what you do want from your pet?

solo questing & leveling?

tanking for you & a friend?

extra dps in a dungeon?

a good mix of damage & armor for pvp?

You can have 5 total pets. See a Stable Master to stable your pet so you can tame a new one.

Pets come in 3 categories of pets

Tenacity – high health, but low damage. These are good for solo questing, leveling or as a tank for a small group. Examples: Bears, boars, crabs, crocolisks, gorillas, rhinos*, scorpids, turtles, warp stalkers, worms*

Ferocity – low armor, but high damage. These are good for extra damage in a group that you already have a tank for. Examples: Carrion Birds, cats, core hounds*, devilsaurs*, hyenas, moths, raptors, spirit beasts*, tallstriders, wasps, wolves